html,body {
  background-color: #fafaff;
  margin: 0 auto;
  padding: 12px;
}
.App {
  width: 1020px;
  margin: 0 auto;
}
.classItem {
  user-select: none;
  position: relative;
  margin-bottom: 24px;
}
.classTitle {
  border-top: 1px solid rgb(230, 235, 245);
  line-height: 64px;
  font-size: 16px;
  color: rgb(110, 110, 110);
}
.classRank {
  display: inline-block;
  transform-origin: left center;
  font-size: 12px;
  color: #ccc;
  transform: scale(0.8);
  margin-left: 6px;
}
.navList {
  width: 960px;
  margin: 0 auto;
}
.navItem {
  position: relative;
  display: inline-block;
  vertical-align: top;
  margin-right: 20px;
  margin-bottom: 12px;
  margin-top: 12px;
  background-color: #fff;
  height: 64px;
  width: 180px;
  font-size: 12px;
  flex-direction: row;
  align-items: center;
  justify-content: space-around;
  text-decoration: none;
  box-shadow: 1px 1px 3px rgba(0, 0, 0, 0.1);
  padding-left: 40px;
}
.navItem:hover {
  box-shadow: 1px 1px 3px rgba(0, 0, 0, 0.25);
}
.navItem:nth-child(4n) {
  margin-right: 0;
}
.navTitle {
  padding-top: 12px;
  padding-bottom: 6px;
  padding-right: 6px;
}
.navIcon {
  position: absolute;
  left: 12px;
  top: 12px;
  display: block;
  border-radius: 3px;
  width: 16px;
  height: 16px;
}
.navTitleText {
  height: 16px;
  line-height: 16px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  font-weight: bold;
  color: #000;
  font-size: 14px;
}
.navDesc {
  color: #adadad;
  line-height: 16px;
  height: 16px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  padding-right: 12px;
}
.topRight {
  position: absolute;
  top: 12px;
  right: 12px;
  display: flex;
}
.userId {
  position: absolute;
  top: 12px;
  left: 12px;
  display: flex;
  font-size: 13px;
  color: #999;
  cursor: pointer;
}
.topBtn {
  margin-left: 12px;
  width: 72px;
  height: 36px;
  background-color: #f1f1f1;
  text-align: center;
  line-height: 36px;
  font-size: 13px;
  color: #666;
  cursor: pointer;
}
.topBtn:hover {
  background-color: #000000;
  color: #fff;
}
.copyright {
  text-align: center;
  font-size: 12px;
  color: #999;
  padding: 24px 0;
}